I'm a researchist and learned a long time ago with motor oil, color means almost everything. I try to determine what color my Amsoil oil is when I first put it in my vehicle to research and then I start to observe how the oil changes color over time. We further research by putting in a dipstick every few days so we can 'read' our engines oil based on its color. Most of the time oil starts to look dark brown after 3,000 miles, and very dark brown after 5,000. Remember though, oil is supposed to be changed every 5K so I'd like to know if your Amsoil oil testing has given you different color readings and at what mileage are you getting it?